-- group of sky divers back on solid ground after their two small planes collided head on in mid air eleven people were on board and every one of those sky divers survived. Parachuting to ground. ABC's Bob Nelson with their harrowing story tonight. Skydive superior is a company whose web site boasts of adrenaline packed moments in the sky. But -- Saturday nine trip was far more than they bargained for all of a sudden. There's this really weird noise that. Is kind of just like up. Boom two planes carrying nine sky divers and two pilots collided Saturday -- 121000 feet in the air in northwest Wisconsin. The trailing plane hit the leading aircraft creating a fire ball. That sheared off the front plane's right wing. That plane was destroyed splitting into three pieces amazingly all nine quick thinking sky divers were able to parachute to safety. One pilot used in emergency parachute but he's got to get a seat belt he's going to get out the door. And then deployed its parachute. And the other was forced to make an emergency landing back at the airport that pilot was the only one injured instructor -- Robinson knows -- far worse tragedy was just narrowly avoided. Very very lucky any time to plans. Collide in there I -- it's. It's potential disaster for everybody involved and so we were all very very lucky. Now -- FAA has launch an investigation into the cause of the accident but. The instructor we talked to for the story believes an unstable air mass created by one of those planes. Is David what could have sparked that Coolidge -- everyone survived which was incredible -- very lucky folks.

This transcript has been automatically generated and may not be 100% accurate.

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